Even before the crash on Tuesday, Orbital had planned to
switch to another engine for future launches, given the age of
Soviet-era motors now in use as well as uncertainty about future
supplies.

Analysts said they expect Orbital to use a motor from
Alliant Techsystems following the planned merger of the
two firms.

More critical will be the potential development of a U.S.
rocket engine that could eventually power both Orbital's Antares
and the Atlas V rocket built by United Launch Alliance, a
Lockheed Martin Corp -Boeing Co joint venture.

The Atlas V rocket is powered by the Russian-built RD-180
engine, which is newer and has had no performance issues.

U.S. lawmakers have earmarked funds in draft budget
legislation for fiscal 2015 to start work on a new engine. Air
Force and Pentagon officials cite broad consensus to end U.S.
dependence on Russian engines and the Soyuz spaceship, currently
the only way for astronauts to reach the International Space
Station.

Pressure could also rise on privately held Space Exploration
Technologies to accelerate its own planned launches. SpaceX, run
by billionaire Elon Musk, is hauling supplies for NASA and
separately seeking certification from the Air Force to carry
military and intelligence satellites.

Authorities are investigating what caused the unmanned
rocket to explode in a fireball moments after liftoff,
destroying about 5,000 pounds of supplies and equipment bound
for the space station.
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